Here's a 2-frame animation (5 sec dwell time for a frame) showing AR1787 (cropped from the left-centre portion of the above image) photographed at H-alpha line centre and at 0.6 Angstroms blue-detuned. (The H-alpha filter has 0.6 Angstrom bandwidth.)
It's interesting to see significant absorption for the blue detuning (in the dipole upper left of centre), identifying hydrogen gas streaming away from the solar surface.
